1. Field of the Invention
This invention relates to a motor-operated pump of the in-tank type, and more particularly to a motor-operated pump of the in-tank type adapted to be sunk in a liquid fuel tank of a vehicle such as an automobile.
2. Description of the Related Art
FIG. 6 is a cross-sectional view of a conventional motor-operated pump of the in-tank type as disclosed in Japanese Laid-Open (Kokai) Patent Application No. 272994/88. In this Figure, reference numeral 1 denotes a motor serving as a pump drive source, reference numeral 2 denotes a rotor of the motor 1, reference numeral 3 denotes a commutator of the rotor 2, reference numeral 4 denotes a brush held in contact with the commutator 3 so as to supply electric power to the rotor 2, reference numeral 5 denotes a shaft of the rotor 2, reference numeral 6 denotes an impeller connected to the shaft 5 and forming the pump, reference numeral 7 denotes an intake port of the pump, reference numeral 8 denotes a pump casing, reference numeral 9 denotes a bracket of the motor 1, reference numeral 10 denotes a cover-out, reference numeral 10a denotes a discharge port of the pump, reference numeral 11 denotes a terminal mounted on the cover-out 10 so as to be supplied with electric power from the exterior, reference numeral 12 denotes a brush spring for urging the brush 4 against the commutator 3, and reference numeral 13 denotes a noise prevention device for preventing electrical noises. Bearings 8a and 9a are mounted on the pump casing 8 and the bracket 9, respectively. The bracket 9 has a through hole 9b receiving the brush 4.
The conventional motor-operated pump of the in-tank type is constructed as described above, and when electric power is supplied to the terminal 11, the electric power is supplied to the rotor 2 via the noise prevention device 13, the brush 4 and the commutator 3. As a result, the rotor 2 is driven, and the impeller 6 connected to the rotor 2 is rotated, and fuel is drawn into the intake port 7 by the rotating impeller 7, and then is fed to an engine or the like (not shown) via the discharge port 10a.
In the above-described conventional motor-operated pump of the in-tank type, the side 3a of the commutator 3 held in sliding contact with the brush 4 are disposed in opposed relation to the bracket 9 and the bearing 9a. Therefore, when the axially-movable rotor 2 is moved due to vibrations or the like, the brush-sliding contact surface 3a of the commutator 3 is brought into contact with a confronting surface 9c of the bracket 9 which results in a problem that the durability of the pump is adversely affected. Also, the brush-sliding contact surface 3a is brought into contact with the bearing 9a, which results in a problem that the performance of the pump is markedly lowered.